WAVELENGTH-DEPENDENT PHOTOLYSIS OF 3-VINYL-PHENYL-AZOSULFONATE

The photochemical decomposition of 3-vinyl-phenyl-azosulphonate (II) in aqueous solution was investigated by pulsed UV laser irradiation. Photolysis at 308 nm results in a complex reaction proceeding via more than one intermediate. In the final products identified by gas chromatography-mass spectroscopy analysis, the azosulpbonate group of II is replaced by a hydroxyl group, and the vinyl group is saturated by the formal addition of a molecule of water. Further hydroxyl groups are introduced on the aromatic ring in other products. Pulsed dye laser irradiation at 370 or 390 nm results in a different behaviour. The parent compound is first converted into an intermediate (X) characterized by an absorption maximum at 272 nm. The latter species may be further decomposed into the final products by subsequent irradiation at 308 nm. A reaction scheme accounting for these observations is proposed, and the identities of the various intermediates are discussed.